In networking terms, quality of service (QoS) refers to a capability of providing different priorities to different applications, users, or data flows or to guarantee a certain level of performance to a data flow. For example, a communications network may have different types of data traffic that have different performance requirements, such as video streaming traffic and data backup traffic. To provide an acceptable video playback experience, the video streaming traffic may require a high level of throughput (e.g., to avoid delays in the playback) and can therefore benefit from a high priority level. In contrast, the data backup traffic can tolerate some measure of lower performance and can therefore be assigned a lower priority where network resources are constrained. In this manner, the video streaming traffic can have greater access to the limited network resources than the data backup traffic so as to maintain the required high level of throughput.
However, Fibre Channel over Ethernet (FCoE) represents a multiprotocol communications standard that allows Fibre Channel (FC) traffic to use an Ethernet network while preserving the FC protocol. This multiprotocol nature of FCoE presents incompatibilities for providing QoS within an FCoE nature. For example, a FC implementation may support a protocol-specific or implementation-specific predetermined number of QoS levels (e.g., eight) and further requires in-order, lossless communications, whereas Ethernet does not support the same QoS scheme and does not require in-order, lossless communications. As such, traffic behaves differently in each protocol. Accordingly, managing QoS within a multiprotocol environment offers a significant technical challenge. Likewise, it is difficult to maintain QoS across protocol boundaries (e.g., between an Ethernet network and a Fibre Channel network).